The present invention relates to a flat-panel display device, and more particularly to a flat-panel display device and display method which can display images of different aspect ratios in an effective display area.
In recent years, as regards flat-panel display devices represented by a liquid crystal display device, a device whose effective display area has an aspect ratio of 9:16 has been developed.
For example, a video signal of an NTSC mode which has image information in an aspect ratio of 3:4 is used as an input signal to the flat-panel display devices, in addition to a video signal of a high vision mode (or EDTV II mode) which has image information in the aspect ratio of 9:16.
If a video signal having image information in the aspect ratio of 3:4 is input to the flat-panel display device whose effective display area has the aspect ratio of 9:16, the aspect ratio of 3:4 is deformed to the aspect ratio of 9:16, with the result that a horizontally expanded image is displayed in the overall effective display area.
Thus, the conventional display device merely has a so-called full display mode in which an image is displayed in the overall display area is effected completely irrespective of the aspect ratio assigned to the video signal. Therefore, the display device cannot display the image in the effective display area while maintaining the aspect ratio of 3:4, for example.
This is because predetermined non-display areas arranged horizontally must be provided in a case where a display operation of a video signal having image information in the aspect ratio of 3:4 is effected without changing the aspect ratio in the display area having the aspect ratio of 9:16. If the video signal having image information in the aspect ratio of 3:4 is sequentially sampled at normal sampling timings, samplings for the non-display areas cannot be completed within a blanking period of the video signal.
To cope with the circumstances, a liquid crystal display device as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 6-27903 is known. The liquid crystal display device includes a signal line driving circuit for driving a plurality of data signal lines which are arranged in the horizontal direction for a matrix array of pixels constituting an effective display area. The signal line driving circuit has first to fourth driver ICs for dividing the data signal lines into blocks and driving the respective blocks of data signal lines. More specifically, the first to third driver ICs drive three blocks of data signal lines corresponding to the NTSC signal image display area, whereas the fourth driver IC drives one block of data signal lines corresponding to the remainder area.
By causing the fourth driver IC to operate while the first to third IC operate, video signals can be distributed to all the associated groups of data signal lines within each horizontal scanning period.
However, when the signal image display area is determined for a different aspect ratio, the display area has a restriction depending on the number of blocks divided by the driver ICs in the above structure. Therefore, the divisional number of blocks divided by the driver ICs must be increased to enhance its flexibility. This results in an increase of the cost.